Nonvolatile memory in disposable inkjet printhead cartridges is typically very small to keep manufacturing costs down. Re-writable nonvolatile memory is more expensive than one-time programmable memory. Because of these constraints, disposable inkjet printheads provide only a course indication of ink remaining due to a small number of ink levels encoded in the printhead's limited nonvolatile memory. When a printhead is moved from one printer to another, it carries only this very coarse ink level indication with it. The new printer must make an assumption about where the actual ink level is between the coarse levels that are reported by the printhead nonvolatile memory. In applications such as business accounting, this is unacceptable because accurate dot counting is important.
What is needed, therefore, is a way to more precisely keep track of the remaining ink level in an inkjet printhead cartridge as the cartridge moves from one printer to another.